1. Field of the Invention
The present invention relates to an image reading apparatus and, more specifically, to an image reading apparatus for reading light reflected from an image surface of an original by means of an image sensor to output image signals of desired areas.
2. Description of the Background Art
Conventionally, image reading apparatuses which read images of an original by means of image sensors and edit the read images variously to output image signals have been used as image input means to computers or as original image reading means for digital type copying machines.
An apparatus has been known as such an image reading apparatus in which one dimensional image sensor comprising image reading elements such as CCDs arranged in a line is placed below a platen glass on which the original is placed, a light source for illumination is moved in a direction (scanning direction) orthogonal to the direction of the arrangement of the image reading elements (array direction), and the light reflected from the original passes through a lens to be received by the one dimensional image sensor.
The image reading apparatus comprises an optical enlarging means which changes the distance between the original and the lens so a to change the size of the image formed on the image sensor for enlarging the original image. Generally, when a copy of equal scale magnification is to be provided, the range in the array direction read by the image sensor extends over both sides of the platen glass and is larger than the maximum width of the original. When an enlarged copy is to be provided by using the optical enlarging means, the range in the array direction read by the image sensor becomes narrower. The range is narrowed down to the central portion of the platen glass as the enlarging magnification is increased.
Now, a digital type copying machine incorporating the above described image reading apparatus and a digital printer has been used for providing an extract from an original of one's resident register or an extract of a copy of one's family register. The extract is provided by copying only the necessary columns of the original, namely, the original of one's resident register or the original of one's family register.
FIG. 14 shows one example of an original of one's family register D1.
The original of one's family register D1 has a margin M of a prescribed width on the right end thereof, a base column A on the left of the margin and columns B to G successively arranged on the left side of the base column A. The base column A is a portion which is always needed to provide an extract of the family register. The number and width of the columns B to G are of various values. The maximum width from the right end to the left end of the columns of the copy D1, that is, the maximum range of images, is generally no more than a prescribed value.
When an extract copy of the family register D1 is to be provided, the base column A and the necessary columns out of the columns B to G must be copied and edited so that they are continuously printed on one paper (this operation is sometimes referred as "column skip edition" or "column skip copying"). For example, when the columns C and F are needed, three columns including these two columns and the base column A are copied by column skip copying, and other columns are not copied.
In the conventional image reading apparatus, the coordinates of four corners of a specified area on the platen glass are inputted by numerical keys provided on an operation panel, and only the image signals in the specified area are outputted as valid out of the images read by the image sensor to provide edition copying of a specified area.
However, in the conventional image reading apparatus, the input of the coordinates of necessary portions (columns) of the original (the copy of the resident register D1) was very troublesome, requiring much time and labor. In addition, miss copies often occur due to erroneous inputs. Even if there is no error in inputs, there was a possibility of a miss copy when the position of the original placed on the platen glass is shifted from the normal position.
Japanese Patent Laying-Open Gazette No. 184047/1986 discloses an image reading apparatus in which a reading start position and a reading end position of the original can be set by a reading range setting portion and only the set range of the original is read by the image sensor. However, in the conventional image reading apparatus, the mechanical structure for reading only the set range by the image sensor becomes complicated. In addition, since the conventional device is for reading only a portion of the original, it is incapable of the above described column skip copying.